ABSTRACT

Pollutants that have often been present in the environment, but whose presence, toxicity, and potential health effects are only now being evaluated are indicated as contaminants of emerging concern (CECs).¹ CECs are increasingly being detected in the aquatic environment and many of them act as so-called endocrine disruptors (EDCs), compounds that alter the normal functions of hormones resulting in a variety of health effects. The worldwide-distributed compounds perfluorooctanoic acid (PFOA) and bisphenol A (BPA) are CECs falling in the EDCs category due to their effects on endocrine receptors.^2,3

Skin samples from the bottlenose dolphin (Tursiops truncatus), a top predator that spends its entire life in the water and, therefore, subject to accumulation and magnification of contaminants, were collected to analyze the impact that environmentally relevant concentrations of CECs may have on global gene expression. Transcriptomic analysis and ex vivo assays⁴ were combined using small skin slices cultured and treated for 24 hours with PFOA or BPA or vehicle.

RNA from dolphin biopsies was labeled and hybridized to a species-specific oligomicroarray.⁵ The skin transcriptome displayed changes related to contaminant exposure, potentially predictive about long-term effects on health, being the genes affected involved in immune modulation, response to stress, lipid homeostasis, and development. Within the genes differentially expressed in the transcriptome after CECs treatment, 4 were tested as potential gene markers of anthropogenic contaminants exposure on skin samples from wild cetaceans. RNA from 12 individuals, including the species Stenella coeruleoalba, Tursiops truncatus, and Grampus griseus were sampled in 3 areas (Adriatic, Ionian, and Tyrrhenian seas). Three out of the 4 genes tested showed higher expression in the samples collected from the Adriatic Sea.

The transcriptomic signature of a dolphin skin could be relevant as classifier for a specific contaminant whilst giving information of the specific geographic location where the marine mammal spent its life, due to the different impact on gene expression exerted by different contamination levels.

Acknowledgements

The authors wish to thank the collaborators from the Italian regional institutes for animal protection ‘Istituto Zoo Profilattico’ (IZS) for the collection of skin samples from stranded animals, and particularly Dr. S Caracappa, from the IZS Sicily, Dr. S Rubini, and Dr. A Toffan from the IZS Lombardia and Emilia-Romagna, Dr. W Mignone, Dr. A Pautasso, and Dr. C Cocumelli from the IZS Piemonte, Liguria and Valle D’Aosta. Wild samples in the Italian marine protected area Santuario Pelagos for Mediterranean Marine Mammals located in the Ligurian basin of the Mediterranean Sea were collected thanks to the collaboration with Prof. MC Fossi and her group at the University of Siena and the ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale) during the scientific cruise “Plastic Buster 2014” (Prot. Num: 0017889/PM).

* Presenting author

Literature Cited

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